Liquid propylene process

POLYMERSCONTAININGSULFUR - POLYSULFIDES] (Vol 19) El Paso liquid propylene process... 

Major Developments since 1980. During the 1980s, two fundamental changes in the polypropylene process led to a breakthrough in terms of improved process economics, energy efficiency, and reduced environmental impact. The first of these changes was the conversion from a diluent process to a process in which liquid propene acts as both reactant and diluent for the reactor slurry. This mode of operation, which is called LIPP (Liquid Propylene Process) leads to a considerable increase in the pressure at which such a process is operated. 

In this process liquid propylene, containing some propane, is mixed with benzene and passed through a reaction tower containing phosphoric acid on kieselguhr as catalyst. The reaction is exothermic and the propane present acts as a quench medium. A small quantity of water is injected into the reactor to... 

In the liquid-phase process, high pressures in the range of 80-100 atmospheres are used. A sulfonated polystyrene cation exchange resin is the catalyst commonly used at about 150°C. An isopropanol yield of 93.5% can be realized at 75% propylene conversion. The only important byproduct is diisopropyl ether (about 5%). Figure 8-4 is a flow diagram of the propylene hydration process. ... 

Another method of manufacturing polypropylene employs the liquid monomer as the polymerization solvent. This process, known as the liquid propylene or bulk-phase process, has a major advantage over the slurry method in that the concentration of the monomer is extremely high. The high concentration increases the rate of the reaction relative to that seen... 

UNIPOL [Union Carbide Polymerization] A process for polymerizing ethylene to polyethylene, and propylene to polypropylene. It is a low-pressure, gas-phase, fluidized-bed process, in contrast to the Ziegler-Natta process, which is conducted in the liquid phase. The catalyst powder is continuously added to the bed and the granular product is continuously withdrawn. A co-monomer such as 1-butene is normally used. The polyethylene process was developed by F. J. Karol and his colleagues at Union Carbide Corporation the polypropylene process was developed jointly with the Shell Chemical Company. The development of the ethylene process started in the mid 1960s, the propylene process was first commercialized in 1983. It is currently used under license by 75 producers in 26 countries, in a total of 96 reactors with a combined capacity of over 12 million tonnes/y. It is now available through Univation, the joint licensing subsidiary of Union Carbide and Exxon Chemical. A supported metallocene catalyst is used today. 

In the bulk process, liquid propylene (polymer grade propylene here too) replaces the hydrocarbon diluent used in the slurry phase process. The PP is continuously withdrawn from the solution and any unreacted monomer is flashed off and recycled. The back end of the process, atactic PP removal and catalyst deactivation and removal, is the same as the slurry process. 

In heterogeneous polymerizations in bulk, the formed polymer is insoluble in its monomer and the polyreaction is performed below the softening point of the polymer. On an industrial scale, this type of process is especially utilized for chain polymerizations, for example, the radical polymerization of liquid vinyl chloride, the polymerization of liquid propylene with Ziegler-Natta or with metallocene catalysts, and the polymerization of molten trioxane. 

Two basic methods of production are in commercial use 11) jhsnrption of propylene in sulfuric acid to form alkyl hydrogen sulfate, followed by the hydrolysis of the estei and (2) by direct hydration with water, using a catalyst. An inherent disadvantage in the lirst process is the need lo handle sulfuric acid. Further, the first process yields liuic more ihan 7() f isopropanol as compared with the second process, in which liquid propylene is used as the charge stock. All direct-hydration processes can he represented by CiH + HO) — CiFLOH + heat. 

Butylraldehyde is produced by a homogeneous catalytic process called hydroformulation in which CO and H2 are added to liquid propylene using a soluble cobalt-containing... 

First commercialized at Georgia Gulfs Pasadena, TX plant in 1994, the Mobil-Badger Cumene process consists of a fixed-bed alkylator, a fixed-bed transalkylator and a separation section (22, 23). Fresh and recycle benzene are combined with liquid propylene in the alkylation reactor where the propylene is completely reacted. Recycled polyisopropylbenzenes are mixed with benzene and sent to the transalkylation unit to produce additional cumene. Trace impurities are removed in the depropanizer column. Byproduct streams consist of LPG (mainly propane contained in the propylene feedstock) and a small residue stream, which can be used as fuel oil. 

Description The process includes a fixed-bed alkylation reactor, a fixed-bed transalkylation reactor and a distillation section. Liquid propylene and benzene are premixed and fed to the alkylation reactor (1) where propylene is completely reacted. Separately, recycled polyisopropylbenzene (PIPB) is premixed with benzene and fed to the transalkylation reactor (2) where PIPB reacts to form additional cumene. The transalkylation and alkylation effluents are fed to the distillation section. The distillation section consists of as many as four columns in series. The depropanizer (3) recovers propane overhead as LPG. The benzene column (4) recovers excess benzene for recycle to the reactors. The cumene column (5) recovers cumene product overhead. The PIPB column (6) recovers PIPB overhead for recycle to the transalkylation reactor. 

Description In the Spheripol process, homopolymer and random copolymer polymerization takes place in liquid propylene within a tubular loop reactor (1). Heterophasic impact copolymerization can be achieved by adding a gas-phase reactor (3) in series. 

Description In the Spheripol process, homopolymer and random copolymer polymerization takes place in liquid propylene within a loop tubular reactor (1). Heterophasic impact copolymerization is done by adding a gas-phase reactor (3) operated in series. Removal of catalyst residue and amorphous polymer is not required. Unreacted monomer is flashed in a two-stage pressure system (2, 4) and recycled back to the reactors. This improves yield and minimizes energy... 

The Wacker-Hoechst process has been practised commercially since 1964. In this liquid phase process propylene is oxidized to acetone with air at 110-120°C and 10-14 bar in the presence of a catalyst system containing PdCl2. As in the oxidation of ethylene, Pd(II) oxidizes propylene to acetone and is reduced to Pd(0) in a stoichiometric reaction, and is then reoxidized with the CuCl2/CuCl redox system. The selectivity to acetone is 92% propionaldehyde is also formed with a selectivity of 2-4%. The conversion of propylene is more than 99%. 

Metallocenes immobilized on solid support materials have been successfully introduced in industry as polymerization catalysts for the production of new application-oriented polymer materials. Industrial polymerizations, which are carried out either as a slurry process in liquid propylene or as a gas-phase process (Section 7.2.3), require that catalysts are in the form of solid grains or pellets soluble metallocene catalysts thus have to be supported on a solid carrier. 

The latest industrial application of metathesis was developed by Phillips who started up a plant in late 1985 at Cbannelview, Texas, on the L ondell Petrochemical Complex with a production capacity of 135,000 t/year of propylene from ethylene. This facility carries out the disproportionation of ethylene and 2-butenes, in the vapor phase, around 300 to 350°C, at about 0.5.10 Pa absolute, with a VHSV of 50 to 200 and a once-througb conversion of about 15 per cent 2-butenes are themselves obtained by the dimerization of ethylene in a homogeneous phase, which may be followed by a hydroisomerization step to convert the 1-butene formed (see Sections 13.3.2. A and B). IFP is also developing a liquid phase process in this area. 

At this point not only were further process simplifications possible but also, and above all, radically new, simplified and more economic processes could be realized I73> 174) in liquid propylene or in the gas phase, completely eliminating the use of solvents (Fig. 58). Furthermore, the particular properties of the support make it possible to prepare the catalyst and, thanks to the replication property, also the polymer in... 

Liquid propylene, gaseous carbon monoxide and hydrogen, and a soluble cobalt catalyst are fed to a high-pressure catalytic reactor. The reactor effluent goes to a flash tank, where all of the solution constituents are vaporized except the catalyst, which is recycled to the reactor. The reaction products are separated from unconsumed reactants in a multiple-unit process, and the product stream, which contains both butyraldehyde and /i-butanol, is subjected to additional hydrogenation with excess hydrogen, converting all of the butyraldehyde to butanol. 

In PP manufacture, modern bulk (liquid monomer) and gas-phase processes have largely replaced the earlier slurry processes in which polymerization was carried out in hydrocarbon diluent. The most widely adopted process for PP is Basell s Spheripol process.317 Homopolymer production involves a pre-polymerization step at relatively low temperature, followed by polymerization in a loop reactor using liquid propylene random co-polymers are produced by introducing small quantities of ethylene into the feed. The pre-polymerization step gives a pre-polymer particle with the capacity to withstand the reaction peak, which occurs on entering the main loop reactor. The addition of one or two gas-phase reactors for EP co-polymerization makes it possible to produce heterophasic co-polymers containing up to 40% of E/P rubber within the homopolymer matrix. 

The most important consequences of the absence of crystallinity are softness, tackiness (the property of a material to adhere to itself), a complete solubility in most low-polarity organic solvents, including ethers and aliphatic hydrocarbons, higher transparency, and lower density with respect to crystalline PP. Other physical properties depend also on the molecular mass of aPP.6 Despite the insolubility of aPP in liquid propylene, its tackiness makes it impossible to produce it in bulk or gas-phase processes, with a solution process at medium temperature likely being the only viable manufacturing process. 

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